Conventional methods for diagnosis of diseases such as influenza requires several manual processes, for example, the lysis of virus particles, viral ribonucleic acid (RNA) extraction and detection of the viral nucleic acid, which are often conducted within the confines of centralized laboratories. The entire protocol takes 5 to 6 hours, and requires skilled operators who are at risk of accidental virus exposure and disease contagion.
This is particularly so in the case of highly infectious diseases, for example, H1N1-2009. In less than a month after the first reported case of H1N1-2009 surfaced in Apr. 23, 2009, 39 countries had reported 8480 cases of H1N1-2009 infection and 72 deaths officially to the World Health Organization (WHO).
Current state of the art methods for diagnosis of diseases include nucleic acid-based molecular diagnosis involving three major steps: (i) deoxyribonucleic acid/ribonucleic acid (DNA/RNA) sample preparation, (ii) nucleic acid amplification by polymerase chain reaction (PCR), and (iii) detection of amplified DNA. With its simplicity and effectiveness, real-time PCR (RT-PCR) remains the most popular and robust method for pathogen detection, although detection methods using DNA microchips, label-free approaches and electrophoretic analysis have also been reported.
A number of miniaturized disease diagnostic devices have also been developed. Most of them are focused on either sample preparation for pathogen DNA/RNA purification or on-chip PCR amplification with built-in microvalves, heaters and sensors. Despite these advances, integration of sample purification and molecular detection remains a major challenge for portable disease diagnostic devices. The lack of multiplexing capability has also limited the applicability of these devices towards detecting viruses such as influenza, enterovirus, and the viruses causing hand, foot and mouth disease, such as Coxsackie virus and Enterovirus, which contain various serotypes with similar patient symptoms. In addition, the typical open device design for external introduction of reagents and release of processed waste are prone to hardware cross contamination and accidental virus exposure.
In view of the above, there remains a need for an improved method for the diagnosis of diseases, which can allow the rapid identification of infected patients for isolation and treatment, as well as an apparatus that can be used for diagnosis in decentralized locations such as airports, train stations and immigration check points to contain the spread of highly contagious diseases, and to alleviate the burden of healthcare personnel in the diagnosis of an overwhelming number of suspect cases.